1. Field of the Invention
The present invention relates to a controller-characteristic changing apparatus, a storage device, a controller-characteristic changing method, and a computer product.
2. Description of the Related Art
Sometimes resonance occurs in the internal mechanism (the unit including a head and an actuator arm, for example) of a disk apparatus. The performance of the entire apparatus including a host computer from drops when such resonance occurs. One approach is to change a controller characteristic of a controller that controls a disk driving unit (a unit including a head and an actuator arm) in a disk apparatus.
Specifically, when the resonance occurs, a head that is hovering above the disk with a minute gap therebetween is influenced by the resonance, making it likely to cause a read fault and a write fault on the disk. For example, when a write fault occurs, the disk apparatus normally repeats the execution of a retry process of writing on the disk apparatus. The repetitive execution of such a retry process results in a longer time for a command process to be performed in the host computer of the disk apparatus. This leads to a drop in the performance of the entire apparatus including the host computer.
As a solution to this problem, there has been proposed; a method of changing a controller characteristic of a controller that controls a disk driving unit in a disk apparatus. For example, Japanese Patent Application Laid-open No. 2004-503893 discloses a method of changing a controller characteristic of a controller that controls a disk driving unit to reduce the influence of resonance that is caused by resonance of an actuator arm. Japanese Patent Application Laid-open No. 2000-298958 discloses a method of changing a controller characteristic of a controller that controls a disk driving unit to reduce the influence of resonance that is caused by deterioration of the disk driving unit.
With the conventional techniques, the influence of an external vibration caused by an external factor cannot be reduced. That is, when an external vibration caused by an external factor occurs in a disk apparatus, a read fault and a write fault to a disk are likely to occur, thus resulting in lower performance of the entire apparatus including the host computer. However, the methods disclosed in Japanese Patent Application Laid-open Nos. 2004-503893 and 2000-298958 merely change the controller characteristic based on resonance or deterioration of a component in the disk apparatus, or simply change the controller characteristic that effectively reduce the influence of resonance, so that the influence of an external vibration caused by an external factor cannot be reduced.